fix(model): allow objects with toBSON() to make it to save()

Fix #8299

lib/model.js

@@ -52,6 +52,10 @@ const modelDbSymbol = Symbol('mongoose#Model#db');
 const modelSymbol = require('./helpers/symbols').modelSymbol;
 const subclassedSymbol = Symbol('mongoose#Model#subclassed');
 
+const saveToObjectOptions = Object.assign({}, internalToObjectOptions, {
+  bson: true
+});
+
 /**
  * A Model is a class that's your primary tool for interacting with MongoDB.
  * An instance of a Model is called a [Document](./api.html#Document).
@@ -244,7 +248,7 @@ Model.prototype.$__handleSave = function(options, callback) {
 
   if (this.isNew) {
     // send entire doc
-    const obj = this.toObject(internalToObjectOptions);
+    const obj = this.toObject(saveToObjectOptions);
 
     if ((obj || {})._id === void 0) {
       // documents must have an _id else mongoose won't know

lib/utils.js

@@ -232,6 +232,13 @@ exports.clone = function clone(obj, options, isArrayChild) {
     return obj.clone();
   }
 
+  // If we're cloning this object to go into a MongoDB command,
+  // and there's a `toBSON()` function, assume this object will be
+  // stored as a primitive in MongoDB and doesn't need to be cloned.
+  if (options && options.bson && typeof obj.toBSON === 'function') {
+    return obj;
+  }
+
   if (obj.valueOf != null) {
     return obj.valueOf();
   }

test/document.test.js

@@ -8141,4 +8141,21 @@ describe('document', function() {
       assert.equal(fromDb.activity.description, 'after');
     });
   });
+
+  it('passing an object with toBSON() into `save()` (gh-8299)', function() {
+    const ActivitySchema = Schema({ description: String });
+    const RequestSchema = Schema({ activity: ActivitySchema });
+    const Request = db.model('gh8299', RequestSchema);
+
+    return co(function*() {
+      const doc = yield Request.create({
+        activity: { description: 'before' }
+      });
+      doc.activity.set({ description: 'after' });
+      yield doc.save();
+
+      const fromDb = yield Request.findOne().lean();
+      assert.equal(fromDb.activity.description, 'after');
+    });
+  });
 });

test/utils.test.js

@@ -340,5 +340,19 @@ describe('utils', function() {
 
       done();
     });
+
+    it('skips cloning types that have `toBSON()` if `bson` is set (gh-8299)', function() {
+      const o = {
+        toBSON() {
+          return 'toBSON';
+        },
+        valueOf() {
+          return 'valueOf()';
+        }
+      };
+
+      const out = utils.clone(o, { bson: true });
+      assert.deepEqual(out, o);
+    });
   });
 });